1. Field of the Invention
The present invention relates to a semiconductor device testing apparatus having connected thereto a semiconductor device transporting and handling apparatus (commonly called handler) for transporting semiconductor devices (such as semiconductor device integrated circuits) for testing purposes, and sorting out the tested semiconductor devices on the basis of the test results, and more particularly to improvements on that portion of the semiconductor device testing apparatus for testing/measuring semiconductor devices to be tested as brought into the testing or test section by the semiconductor device transporting and handling apparatus (as will be referred to as handler hereinafter).
2. Description of the Related Art
As is well known, many semiconductor device testing apparatuses (commonly called IC tester) for testing various types of semiconductor devices including semiconductor device integrated circuits (as will be referred to as IC hereinafter) have a handler connected thereto for transporting a semiconductor device to be tested or under test (commonly called DUT) to the test section to be brought into electrical and mechanical contact with a device-testing socket of the semiconductor device testing apparatus (as will be referred to as IC tester hereinafter) disposed in the test section thereof, and after testing, carrying the tested semiconductor device out of the test section for transport to a predetermined location.
Since the present invention is concerned with the IC tester of the type having a handler connected thereto, one example of the IC tester of this type will first be described with reference to FIGS. 4 and 5. For simplicity of description, the invention will be described in the following disclosure by taking the IC tester designed for testing ICs which are typical of semiconductor devices by example.
FIGS. 4 and 5 are a side view, partly in cross-section, showing the general construction of the conventional IC tester suitable for use for testing multiple-pinned ICs with built-in logic circuitry or analog circuitry among others, and a plan view illustrating the conventional handler, respectively.
The IC tester shown in FIG. 4 comprises a tester proper (which is known as main frame in the art concerned) MF in which electrical and electronic circuits and devices among other components are accommodated, a handler HAND equipped with a transporting mechanism for transporting ICs, and a test head TSH electrically connected with but constructed separately from the tester proper MF and mounted in the test section of the handler HAND.
The handler HAND comprises a base plate 10, and the IC transporting mechanism including first X-Y transport apparatus 20, second X-Y transport apparatus 30, and Z-axis driving apparatus (which is an apparatus adapted to move articles in a vertical direction (upward and downward directions) as viewed in FIG. 4), all being disposed on the base plate 10. Further, the base plate 10 includes an extension extending horizontally as viewed in the drawing beyond the handler and defining a space SP therebelow where the test head TSH is disposed. In addition, the extension of the base plate 10 is formed with a through-aperture 11 sized enough for an IC under test to pass through, so that an IC to be tested may be lowered through this through-aperture 11 to be placed into an IC socket SK mounted on the test head TSH.
ICs under test which have been transported into the test section by the IC transporting mechanism of the handler HAND are brought into electrical contact with the IC socket SK mounted on the test head TSH of the tester proper MF, and hence electrically connected with the tester proper MF through the test head TSH and a bundle of cables KU. A test signal of a predetermined pattern as supplied from the tester proper MF through the bundle of cables KU is applied to the IC under test, and response signals read out of the IC under test are transmitted from the test head TSH to the tester proper MF through the bundle of cables KU to measure the electrical characteristics of the IC.
Accommodated in the test head TSH are mainly a gang of drivers for applying a test signal of a predetermined pattern to ICs under test, a gang of comparators CP each for determining whether the output signals read out of the IC under test are a high (H) logic signal or a low (L) logic signal having a predetermined value of voltage, respectively, power lines, and the like, these components and the power lines being electrically connected with the tester proper MF through the bundle of cables KU.
Upon the test being completed, the tested ICs are carried from the IC socket SK to a predetermined location by the IC transporting mechanism of the handler HAND and subsequently are sorted out on the basis of the test results.
FIG. 5 is a plan view illustrating the general construction of the IC tester, particularly of the handler HAND. This handler HAND includes the first and second X-Y transport apparatus 20 and 30 which are capable of transporting articles in both the X- and Y-axis directions, the first and second X-Y transport apparatus 20 and 30 being disposed on the generally rectangular base plate 10 in longitudinally (in the right to left direction as viewed in the drawing) opposed relation to each other. The longitudinal direction is referred to as X-axis direction herein.
The first X-Y transport apparatus 20 includes a pair of first parallel X-axis rails 21A, 21B extending for a predetermined length in the X-axis direction over and along the opposite major lateral sides of the base plate 10 from adjacent the left end thereof as viewed in the drawing, a first movable arm 26 spanning the X-axis rails 21A, 21B orthogonally therewith and movably mounted on the rails in the X-axis direction therealong, and a first X-Y carrying head 24 mounted on the movable arm 26 for movement therealong in the Y-axis direction.
The second X-Y transport apparatus 30 includes a pair of second parallel X-axis rails 31A, 31B extending for a predetermined length in the X-axis direction over and along the opposite major lateral sides of the base plate 10 from adjacent the left end thereof as viewed in the drawing, a second movable arm 36 spanning the X-axis rails 31A, 31B orthogonally therewith and movably mounted on the rails in the X direction therealong, and a second X-Y carrying head (not shown) mounted on the movable arm 36 for movement therealong in the Y direction.
With this arrangement, the first X-Y carrying head 24 is movable by the first X-Y transport apparatus 20 constructed as described above to any desired point within the generally rectangular area (A) defined between the pair of first X-axis rails 21A, 21B as shown in dotted lines while the second X-Y carrying head is likewise movable by the second X-Y transport apparatus 30 to an) desired point within the generally rectangular area (B) defined between the pair of second X-axis rails 31A, 31B as shown in dotted lines. That is, the area (A) is the region within which the first X-Y transport apparatus 20 is capable of transporting articles while the area (B) is the transportable region of the second X-Y transport apparatus 30.
Disposed in the lower portion of the area (A) successively from the right side to the left side as viewed in the drawing are an empty tray storage section 46 for accommodating empty trays stacked one on another, a feed tray 41 loaded with ICs to be tested (ICs under test), two 42 and 43 of sorting trays 42, 43, 44 and 45 for sorting and storing tested ICs on the basis of the test results. The remaining two sorting trays 44 and 45, and a planar heater plate 50 for heating ICs under test to a predetermined temperature are disposed successively from the left to right side in the upper portion of the area (A) as viewed in the drawing. It is needless to say that the arrangement of the trays 41-45, the empty tray storage section 46 and the heater plate 50 and the number of the sorting trays 42-45 are illustrated herein as only one example and that they may be varied as required.
Disposed within the area (B) is the test section TS of the IC tester within which there are mounted IC sockets with which ICs under test are to be put into electrical contact. As the illustrated handler is configured to test two ICs under test at one time, the test section TS is equipped with two sockets.
The illustrated handler is further provided with first and second buffer stages BF1 and BF2, respectively, which are reciprocally movable in the X-axis direction between a predetermined position in the area (A) and a predetermined position in the area (B). More specifically, the first buffer stage BF1 is reciprocally movable in the X-axis direction between that section within the area (A) adjacent the right hand side of the heater plate 50 and a predetermined position in the area (B) while the second buffer stages BF2 is reciprocally movable in the X-axis direction between that section within the area (A) adjacent the right hand side of the empty tray storage section 46.
The first buffer stage BF1 performs the function of transferring ICs under test heated to a predetermined temperature from the area (A) to the area (B) while the second buffer stages BF2 acts to carry the tested ICs from the area (B) to the area (A). It is to be understood that the provision of these buffer stages BF1 and BF2 permits the first and second X-Y transport apparatus 20 and 30 to accomplish their transport operations with no interference with each other.
The first X-Y transport apparatus 20 described above is configured to convey ICs under test to the heater plate 50 for applying a predetermined temperature stress to the ICS, and then perform the operation of transferring the ICs under test heated to a predetermined temperature onto the first buffer stage BF1 and the operation of transferring the tested ICs from the second buffer stage BF2 onto the predetermined sorting trays which tested ICs have been transported from the area (B) to the area (A) by the second buffer stage BF2.
On the other hand, the second X-Y transport apparatus 30 is configured to perform the operation of transporting ICs under test as conveyed by the first buffer stage BF1 into the area (B) to the test section TS and the operation of transferring the tested ICs from the test section TS onto the second buffer stage BF2.
The heater plate 50 described above may be formed of plate-like metal stock for example, and is provided with a plurality of IC receiving recesses or pockets 51 for accommodating ICs under test. ICs being tested are transported from the feed tray 41 into these IC receiving recesses 51 by the first X-Y transport apparatus 20. These IC receiving recesses 51 are typically arrayed in the form of a matrix composed of a plurality of rows and a plurality of columns. The heater plate 50 is maintained in an elevated temperature somewhat higher than the temperature to which ICs being tested are to be applied. The ICs being tested are thus heated to a predetermined temperature before being transported by means of the first buffer stage BF1 to the test section TS.
The first and second X-Y transport apparatus 20 and 30 are each provided with their own Z-axis driving apparatus (each of which is adapted to convey an IC in a vertical direction (Z-axis direction)) which perform the operation of picking up ICs out of the trays, the heater plate 50 or the test section TS (sockets) and the operation of dropping off ICs onto the trays, the heater plate 50 or the test section TS.
FIG. 6 illustrates the general construction of one example of the Z-axis driving apparatus mounted on the first X-Y transport apparatus 20. The movable arm 26 extending in the Y-axis direction of the first X-Y transport apparatus 20 comprises a hollow member having a generally C-shaped cross-section, in the hollow interior of which a threaded shaft 22 and a guide shaft 23 likewise extending in the Y-axis direction are housed. Specifically, the threaded shaft 22 and guide shaft 23 extend in the Y-axis direction through the body portion of the first X-Y carrying head 24 which is formed with threads engageable with the threads of the threaded shaft 22. The guide shaft 23 has no threads thereon so as to permit sliding movement of the body portion of the first X-Y carrying head 24 relative to the guide shaft 23 which in turn acts to stabilize the movement of the X-Y carrying head 24 in the Y-axis direction.
With the construction as described above, driven rotation of the threaded shaft 22 will move the first X-Y carrying head 24 in the Y-axis direction in a stable manner. It is to be noted that the movement of the X-Y carrying head 24 in the X-axis direction is effected by the movement of the movable arm 26 in the X-axis direction.
Extending horizontally (in the X-axis direction as viewed in FIG. 5) from the top of the body portion of the first X-Y carrying head 24 is an arm 24A on the underside of which are mounted a plurality of vertically downwardly extending air cylinders, four air cylinders in this example, that is, first, second, third and fourth air cylinders S1, S2, S3 and S4 as shown in FIG. 5. In FIG. 6, the second air cylinder S2 is invisible as it is hidden behind the first air cylinder S1. Likewise, the fourth air cylinder S4 is invisible as it is hidden behind the third air cylinder S3. Each of the movable rods of the air cylinders S1, S2, S3 and S4 has a vacuum pick-up head mounted on its lower end.
While in the illustrated example the Z-axis driving apparatus 60 is adapted to actuate the first and second air cylinders S1 and S2 in a pair and the third and fourth air cylinders S3 and S4 in a pair so as to vacuum attract two ICs at a time thereagainst for transport, this is only an example.
One set of the first and second air cylinders S1 and S2 are employed to transport ICs under test heated to a predetermined temperature in the heater plate 50 to the first buffer stage BF1. In view of this, the vacuum pick-up heads 61 (shown as having ICs under test attracted thereagainst) mounted on the first and second air cylinders S1 and S2 are equipped with heaters (not shown) for maintaining the temperature of the heated ICs under test. The vacuum pick-up heads 62 mounted on the other set of the third and fourth air cylinders S3 and S4 are equipped with no heaters, because they are used to transport ICs at their normal temperature. Specifically, the vacuum pick-up heads 62 are used when transporting ICs from the feed tray 41 to the heater plate 50 and the tested ICs from the second buffer stage BF2 to corresponding one of the sorting trays 42, 43, 44 and 45.
The second carrying head, not shown, mounted on the movable arm 36 of the second X-Y transport apparatus 30 is also provided with a Z-axis driving apparatus similar in construction to the Z-axis driving apparatus 60. However, since the second X-Y transport apparatus 30 is positioned in a mirror-image relation with the first X-Y transport apparatus 20, the movable arm 36 has a configuration symmetrical with respect to that of the movable arm 26 as shown in FIG. 6 (the movable arm 26 is open on its right-hand side whereas the movable arm 36 is open on its left-hand side), and four air cylinders are mounted on the left side of the movable arm 36. It should be noted that in the second carrying head as well, the Z-axis driving apparatus is adapted to actuate the first and second air cylinders in a pair and the third and fourth air cylinders in a pair so as to vacuum attract two ICs at a time thereagainst for transport. One set of the air cylinders are employed when transporting ICs under test heated to a predetermined temperature from the first buffer stage BF1 to the test section TS. In view of this, the vacuum pick-up heads mounted on these cylinders are equipped with heaters for maintaining the temperature of the heated ICs under test. The vacuum pick-up heads mounted on the other set of air cylinders are equipped with no heaters and are used when transporting ICs at their normal temperature, that is, from the test section TS to the second buffer stage BF2. It will be apparent to those skilled in the art the construction of the Z-axis driving apparatus may be modified in various ways.
The IC tester of the type as described above is configured to heat ICs under test to a predetermined temperature in the heater plate 50 and test the ICs while maintained at that predetermined temperature. There is a considerably much demand for the IC tester of the type utilizing a simplified type of heater means such as the heater plate 50 as described above, because of the high initial cost of the IC tester of the type utilizing a constant temperature chamber capable of maintaining ICs under test heated at a predetermined temperature and employing the test section TS enclosed in the constant temperature chamber to effect the testing.
On the other hand, the IC sockets SK attached to the test head TSH are associated with a socket guide. FIGS. 7 and 8 illustrate the detailed construction of one example of the socket guide.
FIG. 7 is a schematic cross-sectional view illustrating the arrangement of the test head TSH, the IC sockets SK and the socket guide 35, and FIG. 8 is a plan view illustrating the socket guide 35. Affixed to the top of the test head TSH is an annular coupling 32 called flog ring on the top of which is a performance board PB.
The flog ring 32 is a member for electrically connecting the test head TSH and the performance board PB and has annular arrays of pogo contact pins 33 mounted thereto so as to extend from the surface of the ring. The pogo contact pins (which will be referred to as pogo pin) 33 are movable contact pins supported by springs for movement in a direction perpendicular to the surface of the flog ring 32 and are normally biased by the springs in a sense to protrude from the surface of the flog ring 32. These pogo pins 33 are electrically connected with the terminals extending from the undersurface of the flog ring 32, which terminals are in turn electrically connected with the corresponding cables 34 within the interior of the test head TSH.
Mounted on the top surface of the performance board PB are IC sockets SK, two in this example, the terminals of which are electrically connected via the printed wiring in the performance board PB with the corresponding terminal portions of the performance board PB which are to be contacted with the pogo pins 33. It is thus to be understood that the terminals of the IC sockets are electrically connected with the test head TSH via the printed wiring (conductors) and terminal portions of the performance board PB, the pogo pins 33 and the cables 34.
The socket guide 35 surrounds and is mounted on the upper portions of the peripheries of the IC sockets SK. As illustrated in FIG. 8, the socket guide 35 is formed of a generally rectangular plate-like metal block greater by predetermined dimensions than the planar space occupied by two IC sockets SK and has formed therethrough IC guide apertures 35A at locations corresponding to the IC sockets SK. ICs being tested are inserted through the IC guide apertures 35A into the socket guide 35 to be contacted with the IC sockets SK.
It is the Z-axis driving apparatus mounted on the second X-Y transport apparatus that moves ICs under test vertically (upwardly and downwardly) to place them into contact with the IC sockets SK as described before. In FIG. 7, only the movable rods 60R of the Z-axis driving apparatus on which the vacuum pick-up heads are mounted are shown for convenience of simplicity.
Upstanding from the top surface of the socket guide 35 are two guide pins 35B positioned one approximately at the middle point along each of the opposite sides (sides opposed longitudinally of the socket guide 35) of each of the IC guide aperture 35A. The guide pins 35B are configured to guide the associated movable rod 60R of the Z-axis driving apparatus into position as it is lowered with the ICs under test carried thereby. On the other hand, surrounding and mounted to the movable rod 60R at a predetermined elevation is a plate-like guide member 63 having guide holes 63A formed therethrough in vertical alignment with the corresponding guide pins 35B. These guide holes 63A have an inner diameter to snugly fit over the associated guide pins 35B so that the IC under test vacuum attracted against the vacuum head of the movable rod 60R is precisely guided as it is lowered to place the pins of the IC under test into contact with the corresponding contact pins of the IC socket SK This insures an accurate registration of the IC under test with respect to the IC socket SK.
The guide member 63 has two pairs of protrusions 63B extending downwardly from the bottom surface thereof such that once the pins of the IC being placed into contact with the corresponding contact pins of the IC socket SK, these protrusions 63B hold down the pins of the IC being tested to positively maintain them in electrical contact with the socket pins. While in this example there are two pairs of protrusions 63B since the IC under test has pins extending out from four sides thereof as seen in FIG. 8, a frame-like protrusion may be employed in place of two pairs of protrusions. Further, it is needless to say that at least those portions of such protrusions which are to be contacted with the IC pins are made of electrically insulating material.
It has heretofore been a common practice to provide the socket guide 35 with heater means 36 for heating the socket guide 35 to maintain the temperature of the IC under test heated by the heater plate 50 during the test. However, since the IC guide apertures 35A formed through the socket guide 35 as well as the socket guide 35 itself are exposed to the atmosphere as is seen in FIG. 7, there is a substantial heat loss from the socket guide 35. Consequently, when a high temperature thermal stress on the order exceeding 125.degree. C. was applied to the IC under test heated by the heater plate 50, it was difficult to maintain the temperature of the IC at that high temperature, even if the socket guide 35 had an increased heat capacity.
In addition, although the socket guide 35 is connected to a common point of potential to electromagnetically shield the peripheral portions of the IC sockets SK, the upper portions of the IC guide apertures 35A are exposed and yet no special electromagnetically shielding means is provided on the print wiring in the surface of the performance board PB and ICs to be tested; therefore, these components have no protection against external noises including the noise generated by the handler itself.
In the case where ICs to be tested are multiple-pinned devices with built-in logic circuitry or analog circuitry and others and where such devices are tested for their logic circuitry or analog circuitry in the high frequency region, ICs to be tested, the top surface of the IC sockets SK and the print wiring in the surface of the performance board PB would be very likely to be affected by external noises. The deleterious effects by external noises would cause the serious problem of preventing accurate testing and measuring of ICs to be tested.